Sealing between the cylinder head and the engine block or cylinder block of an internal combustion engine presents challenges because of the forces pushing these two components apart and because that movement can cause high pressure air and combustion gases to flow into fluid passages that extend into the cylinder head and the engine block. The situation may be worse if a combustion seal or gasket fails, because there may be little to prevent high-pressure air or combustion gases flowing from a combustion chamber and along a head gasket into fluid connections between the cylinder head and the engine block.
Intake manifold overpressure (IMOP) events are events where pressures in an intake manifold exceed the pressure of normal operation. The cause of these events may be combustion of the air-fuel mixture, also known as a charge, in an intake system. It is possible for a combustion wave during an IMOP event to pass by a cylinder undergoing an intake cycle. The higher intake manifold pressure and temperature experienced during an IMOP event may push additional hot charge past an open intake valve, which may result in elevated cylinder pressures and early compression ignition of the charge. The additional charge coupled with early combustion could then result in an elevated peak cylinder pressure, which may result in charge leakage. This leakage may then travel between the cylinder head and the engine block, entering fluid connections between the cylinder head and engine block.
Consequently, preventing charge leakage that passes through a combustion seal from leaking into one or more fluid systems through a fluid system interface between the engine's cylinder block and cylinder head is a concern. The fluid systems in question may be coolant and lubricating oil. Supercharging of an engine cylinder by adding high pressure in an intake manifold may cause charge leakage past a combustion seal when an intake manifold overpressure event or IMOP, as described hereinabove, occurs. A configuration that would reduce or eliminate the negative effects that can occur when charge or combustion gases escape into an interface between an engine block and a cylinder head would provide improved reliability and performance for internal combustion engines.